Erythema Induratum as Early and Sole Presentation of Tuberculosis

Abstract

INTRODUCTION The tuberculids are hypersensitivity reactions to Mycobacterium tuberculosis following hematogenous spread from a focus of infection.1 Tuberculids reaction can occur before, concurrently or after diagnosis of tuberculosis (TB). We report a case of an end stage renal failure patient who presented with erythema induratum (EI) and subsequently diagnosed to have tuberculosis infection. CASE PRESENTATION This is a 60 year old Chinese man, with end-stage renal disease on regular haemodialysis, and underlying diabetes mellitus, ischaemic heart disease and dyslipidaemia. He first presented with prolonged fever for 2 weeks. Fever occurred mostly in the evening and was associated with weight loss and night sweat. He denied any history of cough, hemoptysis or pleuritic chest pain. Initial and repeated septic work-up including TB were negative. He was then empirically treated with broad- spectrum antibiotics. After discharged home, he developed multiple painful erythematous nodules on the shin and calf associated with recurrent fever and joint pain, for which he was readmitted. On examination, there were multiple painful erythematous subcutaneous nodules and plaques over both the lower limbs (up to thigh). There was no mucosa involvement. Systemic examination was normal except crepitation over lower zone of left lung. No lymphadenopathy or visceral organomegaly. The ESR and C Reactive protein were elevated, full blood count showed persistent leukocytosis. Serum calcium and ACE (Angiotensin converting enzyme) level were normal. Tuberculin skin test was negative and QuantiFeron TB Gold test was indeterminate. CXR showed new haziness of the left lower zone. CT thorax-abdomen revealed multiple subcentimeter intra-thoracic lymphadenopathy and lung nodules seen at the apical segment of both lower lobes. Skin biopsy was performed and the tissues were sent for TB PCR, culture and histo-pathological examination. The skin biopsy was consistent with erythema induratum. Skin tissue for TB PCR and TB cultures were however negative. In view of underlying immune-compromised state and cutaneous manifestation suggestive of tuberculids, empirical anti-TB was commenced. Fever was resolved after 2 weeks of anti-TB therapy associated with significant clinical improvement. The follow-up CT at two months showed significant resolution of lung nodules. He is currently on maintenance anti-TB treatment. DISCUSSION Tuberculids have recently emerged as the commonest form of cutaneous tuberculosis seen in Hong Kong and Taiwan. Erythema induratum (EI; Bazin's disease) is one of the common forms of tuberculids. Erythema induratum predominantly occur on the lower extremities. It is characterized by symmetrically distributed reddish or dusky blue nodules which may ulcerate. Healing leaves atrophic scars. The tuberculin test is usually strongly positive1. Association with TB is present varies between 28% and 56% in patient with EI2-3. Associated TB may be limited to occult sites and can be easily missed if extensive investigations are not done. Identification of tuberculids may prevent diagnostic delay which may lead to unwanted progression of associated TB1-3. Often it is necessary to obtain skin biopsy to confirm the diagnosis. Tissues for TB culture are customarily negative. EI usually improve rapidly on anti-TB treatment. Cellular immune impairment in end-stage renal disease can facilitate the reactivation of quiescent bacilli in residual lesions as well as the development of an uncontained primary infection. The clinical manifestations tend to be atypical and with lower rates of sputum smear positivity. CONCLUSIONS This case illustrates the importance of screening for internal organ TB for those who presented with tuberculids. Tuberculids may precede the manifestation of TB infection. In patient who presented with erythema nodosum (EN) like lesion and with calf involvement, one should look hard for evidence of TB infection. Pyrexia of unknown origin especially in an immune-compromised patient should also make one think of possibility of chronic infection like TB.